Enzyme in Metabolism

Enzyme in Metabolism Life is impossible without enzymes. Enzymes are elements that accelerate the chemical changes required by life. Without enzymes these changes would be very slow, or would not occur at all, and life would cease.Each enzyme is a special protein adapted to a particular chemical process. Digestive enzymes convert food into fluids that can flow into the blood and to the rest of the body. Other enzymes change digested food so that it releases energy, while other enzymes use energy to make food in the body's substances. 1. Understanding Enzymes According to Mayrback (1952) from Germany, enzymes are protein compounds that can catalyze chemical reactions in the cells and tissues of living things. Enzymes are biocatalysts, meaning organic compounds that speed up chemical reactions. 2. Enzyme Properties The properties of enzymes, namely: a. It's a protein. b. It is a biocatalyst. c. Speeds up chemical reactions by reducing activation energy, namely the initial energy needed to start a chemical reaction. d. Enzymes work specifically, meaning that to change or react with a certain substance you also need a certain substance. e. Works very fast. f. Does not react (does not experience change). g. Does not change the reaction balance. h. It has an active site or catalytic site, which is the part of the enzyme where the substrate combines. i. Foreign substrates that function to inhibit reactions are called inhibitors and those that function to speed up reactions are called activators. 3. Components of Enzymes Based on their constituent components, enzymes are divided into: a. Simple protein enzymes consist of proteins. b. Conjugation enzymes, consisting of proteins and non-proteins.Conjugation enzymes are also called holoenzymes. Holoenzymes consist of:  Apoenzyme (protein), namely the part that is relatively heatresistant (thermolabile) or easily changed and is inactive.  Prosthetics or cofactors (non-protein), namely parts that are relatively heatresistant (100o C)for some time (thermostable). Consists of organic ionssuch as Zn, Fe, Mn, Mg, Na, Ca, CO2, K, NAD, NADP, coenzyme A andorganic compounds such as thiamine, riboflavin, pyridoxine, niac andbiotin.A class of prosthetics consisting of organic compoundsIt is called a coenzyme (which is the active part). 4. How Enzymes Work a. The “Lock and Key” Hypothesis Proposed by Emil Fischer, the way enzymes work is like a lock with a key. 1) Between the enzyme and the substrate there is a rigid union like a key and key. 2) The enzyme has a place to combine with the substrate called the active site , which is the attachment point for the substrate molecule. 3) The attachment site has a certain configuration and only a special substrate is suitable for joining. 4) During the reaction, the enzyme and substrate combine temporarilyform enzymesubstrate complexes. 5) The relationship between the combined enzyme and substrate is a weak relationship, so it is easy to separate again. 6) After the reaction, the reaction products no longer combine with the active site or catalytic site. b. Koshland's hypothesis According to Koshland, enzymes and their active sites are structures that are physically more flexible and there is a dynamic interaction between the enzyme and the substrate. If the substrate combines with the enzyme, changes will occur configuration of the active site of the enzyme, so that the enzyme function is effective. 5. Factors that influence enzyme work a. Temperature 0o C = not active 38oC - 40oC = enzyme activity increases above 40oC = enzyme activity decreases activity decreases 60o C = enzyme activity will stop b. Water c. pH pH depends on the location of the enzyme in question. d. Enzyme concentration The speed of the formation or decomposition of substrate molecules follows the enzyme concentration. e. Inhibitors Inhibitors can be divided into 2 types, namely competitive inhibitors and noncompetitive inhibitors. Competitive inhibitors inhibit the work of enzymes by occupyingthe active site of the enzyme so that the substrate cannot bind to the enzyme. Thisinhibitor can be removed by increasing the substrate concentration. Non-competitiveinhibitors work by occupying another part of the enzyme surface so they can changethe active site. This inhibitor can be removed by increasing the substrate concentration. 6. The role of enzymes a. Reduction, namely the reaction of adding hydrogen, electrons, or removing oxygen. b. Dehydration, namely the reaction of releasing water vapor molecules (H2 O). c. Oxidation, namely the reaction of releasing hydrogen molecules, electrons, or adding oxygen. d. Hydrolysis, namely the reaction of adding H2O to a molecule followed by the breakdown of the molecule at the bond that adds H2O . e. Deaminase, namely the reaction of releasing the amine group (NH2 ). f. Decarboxylation, namely the reaction of releasing CO2 and carboxyl groups(–COOH). g. Phosphorylation, namely the reaction to release phosphate. h. Transferase, namely the reaction of removing a radical